1. Field of the Invention
The present invention relates to a digital signal processing method, a data recording and reproducing apparatus, and a data recording medium, and more particularly to a digital signal processing method, a data recording and reproducing apparatus, and a data recording medium that are suitable for signal processing on a high-density recording medium.
2. Description of the Related Art
Recently, data recording media have become denser. For example, as compared with a CD (Compact Disk), a DVD (Digital Versatile Disk) has a shorter minimum mark length and a higher track density with the track pitch of 0.74 xcexcm that is shorter than half of that of a CD. The user recording capacity of a single-sided, single-layer DVD is 4.7 GB.
As a replacement of a disk in the current generation in which a red laser beam is used, manufacturers are now studying a next-generation super high-density optical disk that uses a violet laser beam (GaN). The user recording capacity of the next-generation optical disk is said to exceed 20 GB. Naturally, it will have a shorter minimum mark length and a shorter track pitch, each about half of that of the DVD. On such a high-density disk, a defect developed during disk manufacturing or dust or a scratch during use, if any, would be twice as large as that on the DVD in view of the relative data length.
For example, on a DVD, product coding (product coding is a coding of an error correction such as a product error correction coding) is performed for a set of 192xc3x97172 DVD data bytes to generate 10 columns of PI parity data for the rows and 16 rows of PO parity data for the columns, as shown in (A) in FIG. 1. As a result, a 208xc3x97182 bytes of ECC (Error Correction Code) block is built. Also, as shown in (B) in FIG. 1, one row of PO parity data is inserted every 12 rows to interleave data with PO parity data.
As shown schematically in FIG. 2, the first row to the 208th row of the first ECC block EB1 are written sequentially on a DVD, followed sequentially by the first row to the 208th row of the second ECC block EB2, and so on.
In this method, up to 16 rows may be erasure-corrected with PO parity data. This means that a disk error caused by a continuous disk defect of up to 6 mm in length may be corrected. A continuous error like this is called generally as a burst error. When the linear density is doubled in this format, the maximum length of a correctable defect will be reduced to 3 mm. On the other hand, five symbols (bytes) may be usually corrected with PI parity data and, if there is no random error, the maximum length of a correctable burst error on a DVD is about 10 xcexcm. Therefore, when the linear density is doubled, the maximum length of a defect correctable with PI parity data will be reduced to 5 xcexcm.
Therefore, if there is a random error, the length of a burst error correctable with PI and PO parity data becomes much shorter in the conventional digital signal processing method and on the data recording medium described above. It should be noted that DVD PO rows are interleaved with data rows, not to distribute burst errors, but to keep the parity data ratio constant and therefore there is no effect of increasing the correction length.
To solve this problem, the number of parity data units may be increased to make the correction length longer. However, this method is disadvantageous to high-density recording because parity data redundancy in the ECC block increases.
In view of the foregoing, it is an object of the present invention to provide a digital signal processing method, a data recording and reproducing apparatus, and a data recording medium capable of increasing the maximum burst-error correctable length relatively easily without increasing redundancy.
It is another object of the present invention to provide a digital signal processing method, a data recording and reproducing apparatus, and a data recording medium capable of distributing relatively short burst errors and thereby increasing the data linear density.
To solve the above problems, there is provided a digital signal processing method for recording and reproducing digital signals of data to and from a recording medium on an ECC block basis, the ECC block including a predetermined number of words of digital signals and parity data generated by product-coding the predetermined number of words of digital signals, wherein, with two consecutive ECC blocks as a set, a sequence of operations is repeated for all rows of the two ECC blocks of the set, the sequence of operations being executed in such a way that positions of an odd-numbered data unit in a first row of one of the ECC blocks of the set and an even-numbered data unit in a first row of the other ECC block are exchanged on a data unit basis and recorded on the recording medium and then positions of an even-numbered data unit in the first row of one of the ECC block and an odd-numbered data unit in the first row of the other ECC block are a exchanged on a data unit basis and recorded on the recording medium.
To solve the above problems, there is provided a data recording and reproducing apparatus that records and reproduces digital signals of data to and from a recording medium on an ECC block basis, the ECC block including a predetermined number of words of digital signals and parity data generated by product-coding the predetermined number of words of digital signals, the apparatus comprising: ECC block generating means for generating ECC blocks by a product-coding method, each ECC block including a predetermined number of words of main data, auxiliary information including a sector address, and parity data: interleaving means for sequentially outputting, with n (nxe2x89xa72) consecutive ECC blocks as a set, kth rows and then (k+1)th rows of the ECC blocks of the set in such a way that first rows of the ECC blocks of the set are output sequentially and then second rows are output sequentially, the consecutive ECC blocks being included in the ECC blocks generated by the ECC block generating means; recording means for recording signals, output by the interleaving means, on the recording medium with frame sync codes attached; reproducing means for reproducing the signals from the recording medium; de-interleaving means for de-interleaving the signals reproduced by the reproducing means based on the sector addresses and for outputting the ECC blocks arranged in an original order; and decoding means for decoding the main data using data in the ECC blocks obtained by the de-interleaving means, wherein; the ECC block generating means sequentially generates a plurality of ECC blocks each composed of a predetermined number of words and each comprising a plurality of divided data sectors each being one of two Mxc3x97(N/2) data sectors generated by dividing an Mxc3x97N data sector composed of the main data and the auxiliary information, into two in a column direction; a predetermined number of bytes of first parity data generated from row-direction elements of the plurality of divided data sectors; and a predetermined number of bytes of second parity data generated from column-direction elements of the plurality of divided data sectors, the first parity data or the second parity data being generated from the row-direction elements of the second parity data or the column-direction elements of the first parity data, with two consecutive ECC blocks, generated by the ECC block generating means, as a set, the interleaving means sequentially outputs kth rows, and then sequentially outputs (k+1)th rows, of two divided data sectors corresponding to each of the ECC blocks in such a way that each of first rows of the two divided data sectors, each belonging to one of the ECC blocks of the set, and corresponding first parity data are output sequentially and then each of second rows is output sequentially and, each time M rows of the two divided data sectors are output, the second parity data is output alternately for one and the other of the two ECC blocks alternately, and the recording means records the signals, output by the interleaving means, with the frame sync codes attached at a regular interval.
To solve the above problems, there is provided a data recording and reproducing apparatus that records and reproduces digital signals of data to and from a recording medium on an ECC block basis, the ECC block including a predetermined number of words of digital signals and parity data generated by product-coding the predetermined number of words of digital signals, the apparatus comprising: ECC block generating means for generating ECC blocks by a product-coding method, each ECC block including a predetermined number of words of main data, auxiliary information including a sector address, and parity data; interleaving means for sequentially outputting, with n (nxe2x89xa72) consecutive ECC blocks of the set, kth rows and then (k+1)th rows of the ECC blocks of the set in such a way that first rows of the ECC blocks of the set are output sequentially and then second rows are output sequentially, the consecutive ECC blocks being included in the ECC blocks generated by the ECC block generating means; recording means for recording signals, output by the interleaving means, on the recording medium with frame sync codes attached; reproducing means for reproducing the signals from the recording medium; de-interleaving means for de-interleaving the signals reproduced by the reproducing means based on the sector addresses and for outputting the ECC blocks arranged in an original order; and decoding means for decoding the main data using data in the ECC blocks obtained by the de-interleaving means, wherein; the ECC block generating means sequentially generates a plurality of ECC blocks each composed of a predetermined number of words and each comprising a plurality of divided data sectors each being one of two Mxc3x97(N/2) data sectors generated by dividing an Mxc3x97N data sector composed of the main data and the auxiliary information, into two in a column direction; a predetermined number of bytes of first parity data generated from row-direction elements of the plurality of divided data sectors; and a predetermined number of bytes of second parity data generated from column-direction elements of the plurality of divided data sectors, the first parity data or the second parity data being generated from row-direction elements of the second parity data or column-direction elements of the first parity data, and with two consecutive ECC blocks, generated by the ECC block generating means, as a set, the interleaving means sequentially outputs kth rows, and then sequentially outputs (k+1)th rows, of two divided data sectors corresponding to each of the ECC blocks in such a way that each of first rows of the two divided data sectors, each belonging to one of the ECC blocks of the set, and corresponding first parity data are output sequentially and then each of second rows is output sequentially and, each time (2xc3x97M) rows of the two divided data sectors are output, the second parity data is output for the two ECC blocks.
To solve the above problems, there is provided a data recording and reproducing apparatus that records and reproduces digital signals of data to and from a recording medium on an ECC block basis, the ECC block including a predetermined number of words of digital signals and parity data generated by product-coding the predetermined number of words of digital signals, the apparatus comprising: ECC block generating means for generating ECC blocks by a product-coding method, each ECC block including a predetermined number of words of main data, auxiliary information including a sector address, and parity data; interleaving means for repeating, with two consecutive ECC blocks as a set, a sequence of operations for all rows of the two ECC blocks of the set, the sequence of operations being executed in such a way that positions of an odd-numbered data unit in a first row of one of the ECC blocks of the set and an even-numbered data unit in a first row of the other ECC block are exchanged on a data unit basis and then positions of an even-numbered data unit in the first row of one of the ECC block and an odd-numbered data unit in the first row of the other ECC block are exchanged on a data unit basis; recording means for recording signals, output by the interleaving medium, on the recording means with frame sync codes attached; reproducing means for reproducing the signals from the recording medium; de-interleaving means for de-interleaving the signals reproduced by the reproducing means based on the sector addresses and for outputting the ECC blocks arranged in an original order; and decoding means for decoding the main data using data in the ECC blocks obtained by the de-interleaving means.
To solve the above problems, there is provided a recording medium on which digital signal of data are recorded on an ECC block basis, the ECC block being generated by product-coding a predetermined number of words of digital signals and parity data, wherein, with two consecutive ECC blocks as a set, a sequence of operations is repeated for all rows of the two ECC blocks of the set, the sequence of operations being executed in such a way that an odd-numbered data unit in a first row of one of the ECC blocks of the set and an even-numbered data unit in a first row of the other ECC block are alternately switched on a data unit basis and then an even-numbered data unit in the first row of one of the ECC block and an odd-numbered data unit in the first row of the other ECC block are alternately switched on a data unit basis.
Even when an error occurs in an ECC block at reproduction time, the error occurrence positions of the reproduced signals after de-interleaving may be at least a predetermined distance apart.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.